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Thursday, October 29, 2009

GLOBAL: Malaria tests minus the blood

GLOBAL: Malaria tests minus the blood

DAKAR, 29 October 2009 (IRIN) - To detect malaria people might soon be able to chew a stick of gum and swipe it over a magnet or scan a finger with ultra-far infrared light. Neither test requires a blood sample.

These are some of the winning proposals for the Bill and Melinda Gates Foundation Grand Challenges awards, which invite researchers to find non-invasive diagnostic alternatives for priority global health conditions such as malaria, tuberculosis and HIV. LINK

Other categories include new strategies to prevent malaria and more effective vaccines.

"It is entirely positive for people not necessarily looking at global health issues to use their skill sets from other disciplines to do so, as they will come at a problem from angles that specialists in the global health community may not have thought of," Gates Foundation spokesperson Melissa Covelli told IRIN.

Beyond blood

Extracting blood or tissue can require advanced skills on the part of health workers or pose high costs for patients, as well as complex logistics chains, many of which do not exist in developing countries, Covelli said.

Non-invasive tests also reduce the potential for HIV exposure, said scientist David Bell at Geneva-based Foundation for Innovative New Diagnostics (FIND). And non-invasive tests are preferable particularly when surveying a disease outbreak, as even a small amount of pain involved in a procedure can be a disincentive for people to seek healthcare.

About one million people are reported to die from malaria every year, mostly in sub-Saharan Africa, according to the World Health Organization (WHO).

But in some countries that have widespread malaria rapid testing, the number of suspected malaria cases has dropped dramatically.

Alternatives to testing blood include testing urine, saliva or sweat; equipment that can scan capillaries or the retina; and electromagnetic properties from crystals, such as hemozoin - an iron-containing pigment which accumulates granules in malaria parasites and is a breakdown product of hemoglobin for malaria.

Challenges

To date, all commercially available malaria tests require extracting blood, according to Bell, partly because up to now it has been more difficult to detect malaria in other body fluids.

But, Bell told IRIN, "New technologies could increase the sensitivity of these non-invasive tests and they could be as good as or better than the [blood-related C] tests that we have now."

Andrew Fung, who is developing the chewing gum test, told IRIN: "By working in a user's mouth this test will operate at a higher temperature, and millions of microscopic particles will be examined across a small surface area [the gum] increasing the test's sensitivity."

Winner Lu from the University of Michigan, who is pioneering the infrared option, told IRIN by tapping into body level vibrations rather than testing molecules, this test is highly sensitive too.

To date one of the drawbacks of the 60 rapid diagnostic tests currently on the market has been that they are unregulated, so while some are quite sensitive and can provide 95-100 percent accuracy, others provide far less accurate results.

Ensuring that only high-quality tests remain in use requires better standardized evaluations, Bell said. This is just starting to happen.

WHO published a report this year assessing many rapid diagnostic tests in use and is working with FIND to evaluate 29 more by 2010.

If Fung, Lu and the some 74 other researchers' concepts work, the most promising among them will be eligible for more funding in the future, Gates Foundation's Covelli said.